This application is a 35 USC 371 application of PCT/DE 00/03697 filed on Oct, 20, 2000.
1. Field of the Invention
The invention relates to a device for the electrical and mechanical connection of two printed circuit boards.
2. Description of the Prior Art
One such device is known for instance from the article entitled xe2x80x9cLeiterplatten flexibel verbindenxe2x80x9d [xe2x80x9cConnecting printed circuit boards flexiblyxe2x80x9d], in Feinwerktechnik and Mexcex2technik 1991, pages 204-205, and includes electrically conductive contact pins which are electrically connected to the conductor tracks of a rigid printed circuit board. The contact pins protrude vertically from the rigid printed circuit board and are optionally further stabilized by a plastic substrate. The end of each of the contact pins that protrudes from the rigid printed circuit board is passed through a respective opening in an elastically flexible film- type printed circuit board and soldered to the conductor tracks on the back side of the film-type printed circuit board. Other devices include contact-pressure connectors or plug-type connectors. A disadvantage of the known devices is the complicated assembly and major effort for producing the contacting means which greatly increase the costs. Soldering the contact pins to the conductor tracks of the elastically flexible film-type printed circuit board, in particular, necessitates one additional soldering process. In the event of mechanical stresses on the soldered connections, which result for instance from vibrational or tensile stresses on the film-type printed circuit board, the soldered connections can rapidly be damaged, making such connections no longer reliable.
With the device of the invention the disadvantages known from the prior art are avoided, and an economical, reliable connection of two printed circuit boards is made possible. Advantageously, the device comprises two parts that are simple to produce. A considerable simplification of assembly results from the fact that a first, preferably elastically flexible printed circuit board can be secured with only a few manipulations securely to a second printed circuit board by the use of the clamping part and the contact pin cooperating with it. The device is very sturdy and reliable, and under vibrational and jarring stresses on the first printed circuit board, it advantageously forms a tension relief for the second printed circuit board because of the elastic flexibility of the clamping part. The clamping part and the contact pin can be produced economically by simple techniques.
An especially reliable fixation of the clamping part to the contact pin is attained in that the clamping part has a recess for leading the contact pin through, from the inner edge of which recess, clawlike protrusions extend toward the contact pin and embrace it on all sides.
It is also advantageous that the recess is surrounded by an annularly embodied portion of the clamping part, which portion, on its outer edge remote from the recess, is bent back toward the recess in such a way that the underside of the backward-bent portion forms an annular bearing region of the clamping part for resting on the first printed circuit board. As a result of the bending, the bearing region is movable relative to the annularly embodied region and always presses itself flat against the conductor track of the first printed circuit board.
It especially advantageous that the clamping part has an encompassing groove, and that the clamping part can be fixed in the opening of the first printed circuit board in such a way that the inner edge of the opening engages the encompassing groove. As a result, the clamping part can be pre-mounted on the first printed circuit board, which facilitates assembly considerably. The first printed circuit board can be firmly clamped in the encompassing groove, so that the clamping part is reliably connected electrically to a conductor track, surrounding the opening, of the first printed circuit board.
It is also advantageous that the portion bent back toward the recess is bent back again in such a way that a further reversely-bent portion extends approximately parallel to the bearing region of the clamping part, and the portion bent back toward the recess and the further reversely-bent portion simultaneously form the side walls of the groove.
Advantageously, the side, remote from the groove, of the further reversely-bent portion forms a second bearing region of the clamping part for resting on the second printed circuit board.
It is also advantageous if axially extending lateral grooves for engagement with the elastically flexible protrusions of the clamping part are embodied on the contact pin and are embodied as closed on their end remote from the second printed circuit board. The grooves enable a reliable embracing of the contact pin, and the closed ends of the grooves form detent edges, behind which the elastically flexible protrusions of the clamping part engage the grooves in barblike fashion. This advantageously prevents a mistaken release or snapping off of the clamping part.
Advantageously, by the nonpositive contact of the elastically flexible protrusions with the contact pin, a force introduction to the bearing region is brought about, so that the bearing region is firmly pressed against the conductor track of the first printed circuit board.
The clamping part can advantageously be embodied in one piece. In a preferred exemplary embodiment, the clamping part is embodied as a stamped and bent part of sheet metal.
However, it is also conceivable to design the clamping part as an elastically flexible plastic part, which is provided with an electrically conductive coating.